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Richard E Kerber - One of the best experts on this subject based on the ideXlab platform.
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transthoracic Biphasic Waveform Defibrillation at very high and very low energies a comparison with monophasic Waveforms in an animal model of ventricular fibrillation
Resuscitation, 2002Co-Authors: Craig B Clark, Yi Zhang, Gudjon Karlsson, Ray L Davies, Richard E KerberAbstract:Abstract The purpose of this study was to compare truncated exponential Biphasic Waveform versus truncated exponential monophasic Waveform shocks for transthoracic Defibrillation over a wide range of energies. Biphasic Waveforms are more effective than monophasic shocks for Defibrillation at energies of 150–200 Joules (J) but there are few data available comparing efficacy and safety of Biphasic versus monophasic Defibrillation at energies of 200 J. Thirteen adult swine (weighing 18–26 kg, mean 20 kg) were deeply anesthetized and intubated. After 15 s of electrically-induced ventricular fibrillation (VF), each pig received truncated exponential monophasic shocks (10 ms) and truncated exponential Biphasic shocks (5/5 ms) in random order. Energy doses ranged from 70 to 360 J. Success was defined as termination of VF at 5 s post-shock. For both Biphasic and monophasic Waveforms success rate rose as energy was increased. Biphasic Waveform shocks (5/5 ms) were superior to 10 ms monophasic Waveform shocks at the very low energy levels (at 70 J, Biphasic: 80±9%, monophasic; 32±11% and at 100 J, Biphasic; 96±3% and monophasic 39±11%, both P 75% was achieved with 200 J (10 J/kg) for both Waveforms. Pulseless electrical activity (PEA) or ventricular asystole occurred in 4 animals receiving monophasic shocks and 1 animal receiving Biphasic shocks. Biphasic Waveform shocks (5/5 ms) for transthoracic Defibrillation were superior to monophasic shocks (10 ms) at low energy levels. Percent success increased with increasing energies. PEA occurred infrequently with either Waveform.
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does electrode polarity alter the energy requirements for transthoracic Biphasic Waveform Defibrillation experimental studies
Resuscitation, 2001Co-Authors: Gudjon Karlsson, Yi Zhang, Ray L Davies, William Coddington, Richard E KerberAbstract:Abstract Background: Electrode polarity may alter the success of Biphasic shocks from implantable systems. Whether the electrode polarity influences the success of transthoracic Biphasic Defibrillation is unknown. We determined the effect of electrode polarity on Biphasic transthoracic Defibrillation in a porcine model. Method: In ten anesthetized adult pigs, 16–28 kg, electrode pads were placed in two different orientations on the chest wall; apex-right parasternal and sternal-vertebral column. Ventricular fibrillation (VF) was electrically induced and allowed to persist for 30 s. Truncated exponential Biphasic shocks (5/3 ms) were delivered at 20, 30, 50, 70 and 100 J. Four shocks at each energy level were delivered to construct energy vs. % success curves for VF termination. Electrode polarity for the first pulse was varied so that the first pulse cathode was either the apex (for apex-parasternal) or sternum (for sternum-vertebral column), or the reverse. The second pulse polarity was always the opposite of the first. Results: VF termination success rose from 0 to 86% as energy increased from 20 to 100 J. Varying the electrode polarity did not alter success rates at any energy level with either electrode pad placement. Conclusion: In this porcine model of transthoracic Defibrillation, varying the Biphasic shock electrode polarity did not alter transthoracic Defibrillation success. Positional labeling of transthoracic Biphasic Defibrillation electrode pads may be unnecessary.
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low energy Biphasic Waveform Defibrillation evidence based review applied to emergency cardiovascular care guidelines a statement for healthcare professionals from the american heart association committee on emergency cardiovascular care and the subc
Circulation, 1998Co-Authors: Richard O Cummins, Peter J Kudenchuk, Mary Fran Hazinski, Richard E Kerber, Lance B Becker, Graham Nichol, Barbara Malanga, Tom P Aufderheide, Edward Stapleton, Karl KernAbstract:Researchers have only recently conducted out-of-hospital human studies that document outcomes of transthoracic Defibrillation using a low-energy Biphasic Waveform shock. The American Heart Association Committee on Emergency Cardiovascular Care (ECC) and its subcommittees included prepublication reports of these studies in this review of transthoracic Biphasic Waveform Defibrillation. The writing group and a panel of invited experts have diligently attempted to assess the quality of the studies reviewed here by using a formal evidence-based template, which is summarized in this statement. The experts most familiar with Defibrillation technology and assessment are often recipients of research support from manufacturers of automated external defibrillators (AEDs). Several of the authors and expert reviewers of this report have signed disclosure statements acknowledging training or research support from one or more AED manufacturers. However, in every case, support was administered through the academic institutions employing those individuals. No one has disclosed receiving personal salary support or consultant’s fees from any AED manufacturer, nor has anyone disclosed that they are or were a shareholder, paid advisor, or member of an advisory board of an AED manufacturer. The same is true of ECC Committee members with one exception, an employee of an AED manufacturer who abstained from discussions of the reviewed material and this statement. The final statement was reviewed and approved by the AHA Science Advisory and Coordinating Committee, 2 ECC science advisors, and 2 AHA vice presidents. These reviewers were familiar with the comments and recommendations of the expert reviewers and their disclosure statements. It was the opinion of the final reviewers that statements by the writing group and reviewers were objective, balanced, and based on known scientific facts and did not appear influenced by the disclosed possible conflicts of interest. This report addresses important clinical questions regarding newly developed AEDs that deliver impedance-compensating, fixed, low-energy …
Wanchun Tang - One of the best experts on this subject based on the ideXlab platform.
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fixed energy Biphasic Waveform Defibrillation in a pediatric model of cardiac arrest and resuscitation
Critical Care Medicine, 2002Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Dawn Jorgenson, Kada Klouche, Carl Morgan, David SnyderAbstract:Objective For adults, 150-J fixed-energy, impedance-compensating Biphasic truncated exponential (ICBTE) shocks are now effectively used in automated defibrillators. However, the high energy levels delivered by adult automated defibrillators preclude their use for pediatric patients. Accordingly, we investigated a method by which adult automated defibrillators may be adapted to deliver a 50-J ICBTE shock for pediatric Defibrillation. Design Prospective, randomized study. Setting A university-affiliated research institution. Subject Domestic piglets. Interventions We initially investigated four groups of anesthetized mechanically ventilated piglets weighing 3.8, 7.5, 15, and 25 kg. Ventricular fibrillation was induced with an AC current delivered to the right ventricular endocardium. After 7 mins of untreated ventricular fibrillation, a conventional manual defibrillator was used to deliver up to three 50-J ICBTE shocks. If ventricular fibrillation was not reversed, a 1-min interval of precordial compression preceded a second sequence of up to three shocks. The protocol was repeated until spontaneous circulation was restored, or for a total of 15 mins. In a second set of experiments, we evaluated a 150-J Biphasic adult automated defibrillator that was operated in conjunction with energy-reducing electrodes such as to deliver 50-J shocks. The same resuscitation protocol was then exercised on piglets weighing 3.7, 13.5, and 24.2 kg. Measurements and Main Results All animals were successfully resuscitated. Postresuscitation hemodynamic and myocardial function quickly returned to baseline values in both experimental groups, and all animals survived. Conclusion An adaptation of a 150-J Biphasic adult automated defibrillator in which energy-reducing electrodes delivered 50-J shocks successfully resuscitated animals ranging from 3.7 to 25 kg without compromise of postresuscitation myocardial function or survival.
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reduced post resuscitation myocardial dysfunction after low energy Biphasic Waveform Defibrillation
2002Co-Authors: T Pellis, Wanchun TangAbstract:Approximately one half of the 2 million deaths that occur each year in the United States are due to cardiovascular disease. Of these, approximately one-third or 350,000 occur suddenly and outside of the hospital. Each minute in the United States one person is the victim of “sudden (cardiac) death” and almost one half of the victims are under 65 years of age [1]. Though the initial success of cardiopulmonary resuscitation (CPR) is approximately 39% (range 13 to 59%), a majority of these victims die within 72 hours, primarily due to heart failure and/or recurrent ventricular fibrillation. CPR itself therefore yields a functional survival rate of only 1.4 to 5% [2, 3]. After successful resuscitation from cardiac arrest myocardial function is substantially impaired such that normal contractile and haemodynamic function are restored over an interval of hours or days. Accordingly, there is evidence that the global ischaemic injury is spontaneously reversed. This has been termed “post-resuscitation myocardial dysfunction” (PRMD), which was initially observed during controlled studies in both pigs and rats [4, 5].
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a comparison of Biphasic and monophasic Waveform Defibrillation after prolonged ventricular fibrillation
Chest, 2001Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Kada Klouche, Heitor P Povoas, Takashi Kamohara, Joe BiseraAbstract:Abstract Study objective To compare the effects of Biphasic Defibrillation Waveforms and conventional monophasic Defibrillation Waveforms on the success of initial Defibrillation, postresuscitation myocardial function, and duration of survival after prolonged duration of untreated ventricular fibrillation (VF), including the effects of epinephrine. Design Prospective, randomized, animal study. Setting Animal laboratory and university-affiliated research and educational institute. Participants Domestic pigs. Interventions VF was induced in 20 anesthetized domestic pigs receiving mechanical ventilation. After 10 min of untreated VF, the animals were randomized. Defibrillation was attempted with up to three 150-J Biphasic Waveform shocks or a conventional sequence of 200-J, 300-J, and 360-J monophasic Waveform shocks. When reversal of VF was unsuccessful, precordial compression was performed for 1 min, with or without administration of epinephrine. The protocol was repeated until spontaneous circulation was restored or for a maximum of 15 min. Measurements and results No significant differences in the success of initial resuscitation or in the duration of survival were observed. However, significantly less impairment of myocardial function followed Biphasic shocks. Administration of epinephrine reduced the total electrical energy required for successful resuscitation with both Biphasic and monophasic Waveform shocks. Conclusions Lower-energy Biphasic Waveform shocks were as effective as conventional higher-energy monophasic Waveform shocks for restoration of spontaneous circulation after 10 min of untreated VF. Significantly better postresuscitation myocardial function was observed after Biphasic Waveform Defibrillation. Administration of epinephrine after prolonged cardiac arrest decreased the total energy required for successful resuscitation.
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low energy Biphasic Waveform Defibrillation reduces the severity of postresuscitation myocardial dysfunction
Critical Care Medicine, 2000Co-Authors: Wanchun Tang, Max Harry Weil, Shijie SunAbstract:Both clinical and experimental studies have demonstrated substantial impairment of ventricular function after resuscitation from cardiac arrest Indeed, postresuscitation myocardial dysfunction has been implicated as a potentially important mechanism, accounting for fatal outcomes after successful resuscitation in 70% of victims within the first 72 hrs. Recent experimental studies implicated the total electrical energy delivered during Defibrillation as an important correlate with the severity of postresuscitation myocardial dysfunction and postresuscitation survival. This prompted us to investigate the option of using lower electrical energy Biphasic Waveform Defibrillation. We compared the effects of low-energy Biphasic Waveform Defibrillation with conventional monophasic Waveform Defibrillation after a short (4 mins), intermediate (7 mins), or prolonged (10 mins) interval of untreated ventricular fibrillation. Biphasic Waveform Defibrillation with a fixed energy of 150 joules proved to be as effective as conventional monophasic damped sine Waveform Defibrillation for restoration of spontaneous circulation, with significantly lower delivered energy. This was associated with significantly less severity of postresuscitation myocardial dysfunction. The low-energy Biphasic Waveform Defibrillation is, therefore, likely to be the future direction of transthoracic Defibrillation in settings of cardiopulmonary resuscitation.
Shijie Sun - One of the best experts on this subject based on the ideXlab platform.
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fixed energy Biphasic Waveform Defibrillation in a pediatric model of cardiac arrest and resuscitation
Critical Care Medicine, 2002Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Dawn Jorgenson, Kada Klouche, Carl Morgan, David SnyderAbstract:Objective For adults, 150-J fixed-energy, impedance-compensating Biphasic truncated exponential (ICBTE) shocks are now effectively used in automated defibrillators. However, the high energy levels delivered by adult automated defibrillators preclude their use for pediatric patients. Accordingly, we investigated a method by which adult automated defibrillators may be adapted to deliver a 50-J ICBTE shock for pediatric Defibrillation. Design Prospective, randomized study. Setting A university-affiliated research institution. Subject Domestic piglets. Interventions We initially investigated four groups of anesthetized mechanically ventilated piglets weighing 3.8, 7.5, 15, and 25 kg. Ventricular fibrillation was induced with an AC current delivered to the right ventricular endocardium. After 7 mins of untreated ventricular fibrillation, a conventional manual defibrillator was used to deliver up to three 50-J ICBTE shocks. If ventricular fibrillation was not reversed, a 1-min interval of precordial compression preceded a second sequence of up to three shocks. The protocol was repeated until spontaneous circulation was restored, or for a total of 15 mins. In a second set of experiments, we evaluated a 150-J Biphasic adult automated defibrillator that was operated in conjunction with energy-reducing electrodes such as to deliver 50-J shocks. The same resuscitation protocol was then exercised on piglets weighing 3.7, 13.5, and 24.2 kg. Measurements and Main Results All animals were successfully resuscitated. Postresuscitation hemodynamic and myocardial function quickly returned to baseline values in both experimental groups, and all animals survived. Conclusion An adaptation of a 150-J Biphasic adult automated defibrillator in which energy-reducing electrodes delivered 50-J shocks successfully resuscitated animals ranging from 3.7 to 25 kg without compromise of postresuscitation myocardial function or survival.
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a comparison of Biphasic and monophasic Waveform Defibrillation after prolonged ventricular fibrillation
Chest, 2001Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Kada Klouche, Heitor P Povoas, Takashi Kamohara, Joe BiseraAbstract:Abstract Study objective To compare the effects of Biphasic Defibrillation Waveforms and conventional monophasic Defibrillation Waveforms on the success of initial Defibrillation, postresuscitation myocardial function, and duration of survival after prolonged duration of untreated ventricular fibrillation (VF), including the effects of epinephrine. Design Prospective, randomized, animal study. Setting Animal laboratory and university-affiliated research and educational institute. Participants Domestic pigs. Interventions VF was induced in 20 anesthetized domestic pigs receiving mechanical ventilation. After 10 min of untreated VF, the animals were randomized. Defibrillation was attempted with up to three 150-J Biphasic Waveform shocks or a conventional sequence of 200-J, 300-J, and 360-J monophasic Waveform shocks. When reversal of VF was unsuccessful, precordial compression was performed for 1 min, with or without administration of epinephrine. The protocol was repeated until spontaneous circulation was restored or for a maximum of 15 min. Measurements and results No significant differences in the success of initial resuscitation or in the duration of survival were observed. However, significantly less impairment of myocardial function followed Biphasic shocks. Administration of epinephrine reduced the total electrical energy required for successful resuscitation with both Biphasic and monophasic Waveform shocks. Conclusions Lower-energy Biphasic Waveform shocks were as effective as conventional higher-energy monophasic Waveform shocks for restoration of spontaneous circulation after 10 min of untreated VF. Significantly better postresuscitation myocardial function was observed after Biphasic Waveform Defibrillation. Administration of epinephrine after prolonged cardiac arrest decreased the total energy required for successful resuscitation.
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low energy Biphasic Waveform Defibrillation reduces the severity of postresuscitation myocardial dysfunction
Critical Care Medicine, 2000Co-Authors: Wanchun Tang, Max Harry Weil, Shijie SunAbstract:Both clinical and experimental studies have demonstrated substantial impairment of ventricular function after resuscitation from cardiac arrest Indeed, postresuscitation myocardial dysfunction has been implicated as a potentially important mechanism, accounting for fatal outcomes after successful resuscitation in 70% of victims within the first 72 hrs. Recent experimental studies implicated the total electrical energy delivered during Defibrillation as an important correlate with the severity of postresuscitation myocardial dysfunction and postresuscitation survival. This prompted us to investigate the option of using lower electrical energy Biphasic Waveform Defibrillation. We compared the effects of low-energy Biphasic Waveform Defibrillation with conventional monophasic Waveform Defibrillation after a short (4 mins), intermediate (7 mins), or prolonged (10 mins) interval of untreated ventricular fibrillation. Biphasic Waveform Defibrillation with a fixed energy of 150 joules proved to be as effective as conventional monophasic damped sine Waveform Defibrillation for restoration of spontaneous circulation, with significantly lower delivered energy. This was associated with significantly less severity of postresuscitation myocardial dysfunction. The low-energy Biphasic Waveform Defibrillation is, therefore, likely to be the future direction of transthoracic Defibrillation in settings of cardiopulmonary resuscitation.
Max Harry Weil - One of the best experts on this subject based on the ideXlab platform.
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fixed energy Biphasic Waveform Defibrillation in a pediatric model of cardiac arrest and resuscitation
Critical Care Medicine, 2002Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Dawn Jorgenson, Kada Klouche, Carl Morgan, David SnyderAbstract:Objective For adults, 150-J fixed-energy, impedance-compensating Biphasic truncated exponential (ICBTE) shocks are now effectively used in automated defibrillators. However, the high energy levels delivered by adult automated defibrillators preclude their use for pediatric patients. Accordingly, we investigated a method by which adult automated defibrillators may be adapted to deliver a 50-J ICBTE shock for pediatric Defibrillation. Design Prospective, randomized study. Setting A university-affiliated research institution. Subject Domestic piglets. Interventions We initially investigated four groups of anesthetized mechanically ventilated piglets weighing 3.8, 7.5, 15, and 25 kg. Ventricular fibrillation was induced with an AC current delivered to the right ventricular endocardium. After 7 mins of untreated ventricular fibrillation, a conventional manual defibrillator was used to deliver up to three 50-J ICBTE shocks. If ventricular fibrillation was not reversed, a 1-min interval of precordial compression preceded a second sequence of up to three shocks. The protocol was repeated until spontaneous circulation was restored, or for a total of 15 mins. In a second set of experiments, we evaluated a 150-J Biphasic adult automated defibrillator that was operated in conjunction with energy-reducing electrodes such as to deliver 50-J shocks. The same resuscitation protocol was then exercised on piglets weighing 3.7, 13.5, and 24.2 kg. Measurements and Main Results All animals were successfully resuscitated. Postresuscitation hemodynamic and myocardial function quickly returned to baseline values in both experimental groups, and all animals survived. Conclusion An adaptation of a 150-J Biphasic adult automated defibrillator in which energy-reducing electrodes delivered 50-J shocks successfully resuscitated animals ranging from 3.7 to 25 kg without compromise of postresuscitation myocardial function or survival.
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a comparison of Biphasic and monophasic Waveform Defibrillation after prolonged ventricular fibrillation
Chest, 2001Co-Authors: Wanchun Tang, Max Harry Weil, Shijie Sun, Kada Klouche, Heitor P Povoas, Takashi Kamohara, Joe BiseraAbstract:Abstract Study objective To compare the effects of Biphasic Defibrillation Waveforms and conventional monophasic Defibrillation Waveforms on the success of initial Defibrillation, postresuscitation myocardial function, and duration of survival after prolonged duration of untreated ventricular fibrillation (VF), including the effects of epinephrine. Design Prospective, randomized, animal study. Setting Animal laboratory and university-affiliated research and educational institute. Participants Domestic pigs. Interventions VF was induced in 20 anesthetized domestic pigs receiving mechanical ventilation. After 10 min of untreated VF, the animals were randomized. Defibrillation was attempted with up to three 150-J Biphasic Waveform shocks or a conventional sequence of 200-J, 300-J, and 360-J monophasic Waveform shocks. When reversal of VF was unsuccessful, precordial compression was performed for 1 min, with or without administration of epinephrine. The protocol was repeated until spontaneous circulation was restored or for a maximum of 15 min. Measurements and results No significant differences in the success of initial resuscitation or in the duration of survival were observed. However, significantly less impairment of myocardial function followed Biphasic shocks. Administration of epinephrine reduced the total electrical energy required for successful resuscitation with both Biphasic and monophasic Waveform shocks. Conclusions Lower-energy Biphasic Waveform shocks were as effective as conventional higher-energy monophasic Waveform shocks for restoration of spontaneous circulation after 10 min of untreated VF. Significantly better postresuscitation myocardial function was observed after Biphasic Waveform Defibrillation. Administration of epinephrine after prolonged cardiac arrest decreased the total energy required for successful resuscitation.
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low energy Biphasic Waveform Defibrillation reduces the severity of postresuscitation myocardial dysfunction
Critical Care Medicine, 2000Co-Authors: Wanchun Tang, Max Harry Weil, Shijie SunAbstract:Both clinical and experimental studies have demonstrated substantial impairment of ventricular function after resuscitation from cardiac arrest Indeed, postresuscitation myocardial dysfunction has been implicated as a potentially important mechanism, accounting for fatal outcomes after successful resuscitation in 70% of victims within the first 72 hrs. Recent experimental studies implicated the total electrical energy delivered during Defibrillation as an important correlate with the severity of postresuscitation myocardial dysfunction and postresuscitation survival. This prompted us to investigate the option of using lower electrical energy Biphasic Waveform Defibrillation. We compared the effects of low-energy Biphasic Waveform Defibrillation with conventional monophasic Waveform Defibrillation after a short (4 mins), intermediate (7 mins), or prolonged (10 mins) interval of untreated ventricular fibrillation. Biphasic Waveform Defibrillation with a fixed energy of 150 joules proved to be as effective as conventional monophasic damped sine Waveform Defibrillation for restoration of spontaneous circulation, with significantly lower delivered energy. This was associated with significantly less severity of postresuscitation myocardial dysfunction. The low-energy Biphasic Waveform Defibrillation is, therefore, likely to be the future direction of transthoracic Defibrillation in settings of cardiopulmonary resuscitation.
Peter J Kudenchuk - One of the best experts on this subject based on the ideXlab platform.
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low energy Biphasic Waveform Defibrillation evidence based review applied to emergency cardiovascular care guidelines a statement for healthcare professionals from the american heart association committee on emergency cardiovascular care and the subc
Circulation, 1998Co-Authors: Richard O Cummins, Peter J Kudenchuk, Mary Fran Hazinski, Richard E Kerber, Lance B Becker, Graham Nichol, Barbara Malanga, Tom P Aufderheide, Edward Stapleton, Karl KernAbstract:Researchers have only recently conducted out-of-hospital human studies that document outcomes of transthoracic Defibrillation using a low-energy Biphasic Waveform shock. The American Heart Association Committee on Emergency Cardiovascular Care (ECC) and its subcommittees included prepublication reports of these studies in this review of transthoracic Biphasic Waveform Defibrillation. The writing group and a panel of invited experts have diligently attempted to assess the quality of the studies reviewed here by using a formal evidence-based template, which is summarized in this statement. The experts most familiar with Defibrillation technology and assessment are often recipients of research support from manufacturers of automated external defibrillators (AEDs). Several of the authors and expert reviewers of this report have signed disclosure statements acknowledging training or research support from one or more AED manufacturers. However, in every case, support was administered through the academic institutions employing those individuals. No one has disclosed receiving personal salary support or consultant’s fees from any AED manufacturer, nor has anyone disclosed that they are or were a shareholder, paid advisor, or member of an advisory board of an AED manufacturer. The same is true of ECC Committee members with one exception, an employee of an AED manufacturer who abstained from discussions of the reviewed material and this statement. The final statement was reviewed and approved by the AHA Science Advisory and Coordinating Committee, 2 ECC science advisors, and 2 AHA vice presidents. These reviewers were familiar with the comments and recommendations of the expert reviewers and their disclosure statements. It was the opinion of the final reviewers that statements by the writing group and reviewers were objective, balanced, and based on known scientific facts and did not appear influenced by the disclosed possible conflicts of interest. This report addresses important clinical questions regarding newly developed AEDs that deliver impedance-compensating, fixed, low-energy …
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prospective evaluation of the effect of Biphasic Waveform Defibrillation on ventricular pacing thresholds
Journal of Cardiovascular Electrophysiology, 1997Co-Authors: Peter J Kudenchuk, Jeanne E Poole, Lee G Dolack, Marye J Gleva, Jill Anderson, Charles Troutman, Gust H BardyAbstract:Effect of Defibrillation on Pacing Thresholds. Introduction: Significant increases in ventricular pacing threshold have been observed following monophasic Waveform ventricular Defibrillation shocks. High-output pacing is recommended to ensure consistent capture, particularly in pacemaker-dependent patients who are likely to be defibrillated. Whether Biphasic Waveform Defibrillation compounds this problem is not known. The purpose of this prospective study was to examine serial changes in ventricular pacing thresholds following single, multiple, low- and high-energy Biphasic Defibrillation sbocks from an implanted defibrillator. Methods and Results: Bipolar pacing thresholds before and after Defibrillation, and the adequacy of pacing capture at three times preshock threshold in the immediate aftermath of ventricular Defibrillation, were prospectively evaluated in 67 consecutively tested recipients of a Biphasic implanted cardioverter defibrillator. Overall, serial pacing thresholds following successful Defibrillation were completely unchanged after 141 of 177 (80%) ventricular fibrillation inductions. In no case did the threshold pulse width increment > 0.06 msec from its baseline value after shock, nor did pacing at a pulse width of three times preshock threshold from dedicated bipolar pacing electrodes fail to result in successful ventricular capture. Changes in threshold were not related to when measured from the time of shock, Defibrillation energy, number of shocks, electrode system, chronicity of leads, shock orientation, or to clinical factors. Conclusions: No clinically important changes in pacing threshold were observed after Biphasic Waveform Defibrillation. Bradycardia pacing at conventional pacemaker outputs of three times baseline pulse width threshold from bipolar electrodes dedicated exclusively to pacing or sensing (but not Defibrillation) consistently allowed for an adequate safety margin following Defibrillation.
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electrode system influence on Biphasic Waveform Defibrillation efficacy in humans
Circulation, 1991Co-Authors: Gust H Bardy, C Troutman, George Johnson, Rahul Mehra, Jeanne E Poole, G L Dolack, Peter J Kudenchuk, David M GartmanAbstract:BACKGROUNDSeveral clinical studies have demonstrated a general superiority of Biphasic Waveform Defibrillation compared with monophasic Waveform Defibrillation using epicardial lead systems. To test the breadth of utility of Biphasic Waveforms in humans, a prospective, randomized evaluation of Defibrillation efficacy of monophasic and single capacitor Biphasic Waveform pulses was performed for two distinct nonthoracotomy lead systems as well as for an epicardial electrode system in 51 cardiac arrest survivors undergoing automatic defibrillator implantation.METHODS AND RESULTSThe configurations tested consisted of a right ventricular-left ventricular (RV-LV) epicardial patch-patch system, an RV catheter-chest patch (CP) nonthoracotomy system, and a coronary sinus (CS) catheter-RV catheter nonthoracotomy system. For each configuration, the Defibrillation current and voltage Waveforms were recorded via a digital oscilloscope to measure Defibrillation threshold voltage, current, resistance, and stored energy....